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Re: Floating CSRs [was Re: Address of second TMSCP controller]

On 3/21/21 9:36 AM, Johnny Billquist wrote:
On 2021-03-21 06:24, Dave McGuire wrote:
On March 20, 2021 5:09:00 PM Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:
Given the retrocomputing geeks who want to run systems as original as
feasible, even to the point of doing things like trying to find
original parts for power supplies and the like, I suspect some would
want to use the floating-CSR rules simply bceause they were The Way It
Was Done Back Then.

   That's precisely the mindset at the museum, with DEC and other systems.

Which is kindof weird, because pretty much noone, nowhere, that I know of, did it that way back then.

I've had the opposite experience. Many years ago, in two jobs that had PDP-11s, and several after that had VAXen, they were all configured according to those rules. All were installed by DEC, and most were under DEC maintenance. One installation was under third-party maintenance.

But perhaps the biggest reason why I enforce it on the DEC machines at LSSM is that I was taught that it was "the proper way" by my DEC mentor in the 1980s, and it stuck with me.

The only truly practical reason that I've heard in support of following those rules is that you can still get through your sysgen etc even if you've added a board and forgotten/lost your notes/etc where you put the CSR! ;)

In those installations, I can recall only one instance of hardware being added to an existing system (a tape drive was added to a MicroVAX 3600) so I can't say whether or not it was common to keep up with those rules in the field. On my personal systems at home it was pretty common to throw in whatever new peripheral I was able to get my hands on, but in the production environments, we already had what we needed and just used it.

But either way, to me it's with the extra effort to have a neat and tidy system that conforms to the documentation, and it's really not that hard to do. Though I've never experienced this with DEC hardware, I've "inherited" several networks at work over the years in which my predecessors had just "thrown things together any old way", causing much cussing and gnashing of teeth. I don't do *anything* that way.

Really. If "retrocomputing geeks" are doing this, it's very different from how it used to be done back when it wasn't "retro".

Well, again that depends on your environment. My experience in business production environments was very different.


Dave McGuire, AK4HZ
New Kensington, PA

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